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I watched your refining video and since this is a hobby of mine I thought I would share some information that might help you on your path. These are all things I learned some from others and some by experimentation but mostly from goldrefining.com and the book by CM Hoke, refining precious metal waste.
You are more than welcome to share this information as you see fit, except for my email please.
A quick word of caution, I see you have good ventilation with your fan but others might not know that the NO and NO2 gas from the nitric acid and Aqua Regia reactions can cause pulmonary edema sometimes delayed by hours. This is bad to really bad, enough about that.
Free advice being worth all you pay, its hard to say what uninvited advice is worth, haha, but here goes.
1. Put your placer in a melting dish and incinerate the gold (heat to red but try not to melt it) this helps to oxidize some of the base metals saving you time and chemicals.
2. Do a boil in 50/50 muriatic acid and distilled water, best method is to sit the beaker in a little bit of sand, I use a ceramic frying pan to hold the sand and beaker in case you brake your beaker or boil over. Your cooker will help cotain the fumes, that rust anything they contact. Heat for 15-30 minutes.
3. Pour through a wetted filter paper and rinse with very hot water, this removes your lead as lead chloride, which is soluable in hot water. This also removes any tin before you introduce your nitric, that's my guess about the white stuff in your video. It's called stannic paste, or stannic acid, most of the other things it's called you can't say in mixed company.
4. Repeat step 1.Put your placer in a melting dish and incinerate the gold (heat to red but try not to melt it) this gets rid of any remaining chlorides, so you don't loose any gold.
5. Rinse your beaker well and make enough 50/50 nitric and distilled water to cover you gold by an inch or more. Remember the "add acid to water rule" heat for 15-30 minutes. This wash water will contain silver. You'll recover that later.
6. Rinse three times with hot water, decanting rinse water and leaving your gold in the beaker.
7. Add all the HCl (muriatic acid) needed to solvate your gold see ratio below.
8. Add 2ml of 3% H2O2 (hydrogen peroxide),this jump starts the production of hydronium in the solution.
9. Heat to around 150*F,
10. Slowly add 25% of the nitric acid, wait for the reaction to slow,
11. Add 25% more, wait for the reaction to slow again.
12. Heat to 190*F, glass candy thermometers work well for this but inferred thermometers are better.
13. Add 25% of the nitric acid and let the reaction slow again.
14. Slowly add only enough of the remaining nitric to dissolve the gold. This step buys you extra gold, so don't rush it.
15. Pour your auric chloride solution through a wetted filter into two volumes of distilled water. As you dilute the solution this will drop any silver as silver chloride and make the solution cloud slightly.
16. Add .5 gram of sulfamic acid crystals (ace hardware) or a couple drops of sulfuric acid if you don't have the sulfamic. Sulfamic Acid will convert any excess nitric acid into Nitrous Oxide and sulfuric acid. Which ever way the sulfuric acid gets into the solution it will drop any lead as lead sulfate. Lead sulfate is insoluble in water and this solution.
17. Let stand overnight to settle, and decant or siphon off your bright, clear, yellow solution. You can filter it if you need to for time but I would start with two wet filters and plan to run the solution through twice, it will go slowly because of the silver chloride. If you have a buchner funnel it's faster.
18. Drop the gold with the SMB like you did in your video.
19. Test and Pour off your now barren solution, save it for now.
20. Rinse your gold mud with hot water, three times
21. Put your gold in a melting dish and incinerate (heat to red but try not to melt it)
22. Boil in 50/50 muriatic acid and water, 15 minutes.
23. Pour into wetted filter rinse with hot water.
24. Place filter with gold in melting dish.
25. Slowly heat with low flame to red, burning away filter paper, then add a pinch of anhydrous borax and melt your now +98% pure gold.
26. The borax will tell you a lot about your gold purity, it will be very clear when your purity is over 99%
27. If you want it to be +99.5% pure, repeat steps 7-22 before melting.
Aqua Regia
Approx 1mL of 70% HNO3 added to 4ml of 30% HCL to dissolve 1g of pure Gold.

Stannic Chloride
You can make your own stannous test solution with a little tin metal; lead free solder, lead free fishing weights or eBay will get you some. Shave the tin into a dropper bottle with muriatic acid, a couple of grams in 10ml of acid. The key is to have a little extra tin in the container to know you have enough. Then just dip a q-tip in your gold solution and put a drop of your stannous on it. It will show purple for gold, the darker the better. It looks black when your lucky. If it turns green or red you have other good news.

Anhydrous Borax
This is the best flux for pure gold, in a pinch though 20 mule team borax works. It will expand ten fold as you heat it up and drive off the water.

Material
If you need Borax or tin, say the word and I can drop a care package in the mail, it would be my pleasure to do so and I have some on hand so no need worry about cost.

Method
The reason for heating the gold to red before melting is to drive off the residual nitrates or chlorides both will volatilize your gold if you don't drive them off before melting.

The reason I said to keep your solution after you drop your gold, is there is a bit of gold left. You mix all your waste solutions together then add a piece of scrap copper. It will drop any silver, gold, and platinum group metals. The precious metals will form as a dark residue on the copper and fall to the bottom. I can help you with those later if you need a hand. After you filter those precious metal residues out, you can use lye to raise the ph to 12 and all the remaining metals will drop as hydroxides, filter those out dry and dispose. Add muriatic to drop ph to 7 and you will have salt water and CO2, I evaporate mine to dry salt in an old crock pot.

I know what you mean about wanting to do it right but getting it done fast. It's like me wanting to be rich and handsome, eh nope, it's not like that at all because you can do this type of refining fast or right, and I'm not rich or handsome, haha.
The big hitters for improvement to what you were doing;
1. Move the sulfuric acid to later in the process after your gold is in solution, so you don't make lead sulfate in the early stages. This will help you a lot, a very small amount of lead will make your gold tend to be brittle and PbSO4 is a pain in the butt to get rid of because it's not soluble like PbCl2
2. Incinerate, Incinerate, incinerate.
This gets rid of organics, like dead seamonsters from the water, the oil from your hands, jet dry, soap you name it. All these things have gold adsorbing carbon in them and will float away with your gold ions in tow.
It also drives off the last acid you were working with, they burn off in this order chlorides, nitrates, then sulfates.
3. Save everything, for now. Things you haven't thought about may become clear later and you don't want to smack yourself in the forehead like me and wish you still have that stuff you threw out.
Remember if gold finds a little copper or iron to precipitate on it looks black! That ain't fair to do that to guys like us, right? So for now any filtrate you catch save in a plastic bottle then when you have a little pile of it, incinerate it and flux it with 2 volumes of borax and a pinch of saltpeter, (KNO3/Potassium nitrate) when you do this the Niter salt oxidizes the base metals to their Oxide state, which bumps the melting temp way up. This makes it easy to suspend the oxide in the molten borax and not alloy with your precious metals. For instance Copper melts at 1984*F, CuO melts 2419*F Tin melts at 450*F Tin oxide 2977*F. So you can see how this helps. These base metal oxides are where the cool color swirls in flux come from.Howdy Ray,

I sorry you had a rough time but, think of it as a way to learn a bunch of hard lessons at once and get them out of the way.

I watched your video and made some notes like we talked about, and even though we spoke about many of these topics I'll list them here for reference.
Where I work we start every meeting off with a safety topic, so here goes:
•Be sure to close your containers between steps, that H2SO4 could be a life changing accident if you knocked it over.
•Use a plastic mortar pan on top of bench to put your beakers, hot plate, and such in to catch spills, boil overs, and drips.
•A bowl of baking soda near by when working with acids would be a great safety aid, you can keep it in a plastic bag between uses.
•last safety note, this time.
Process
•when adding salt to HCl, do it in a separate beaker then pour the acid into the beaker with your gold, leaving any undissolved salt in the beaker.
•10m0s Pour the HCl/gold into a filter, then rinse with very hot water until clear. Cold water will precipitate PbCl (lead chloride)
•put the filter in the dish when you incinerate the gold and burn it away.
•Aqua Regia (AR)it takes 1ml nitric acid and 4 ml HCl to dissolve 1 gram of pure gold.
•18min I think you had used up the HCl so when you were adding nitric it wasn't making AR
•22m24s iron and other base metals can make the yellow color you're asking about.
•23m20s you have excess nitric left, that's why it so reactive.
•24m sorry buddy that sucks, weigh the SMB out, it should only take same weight as your gold. Add it a little at a time with a plastic spoon. When dropping your gold try to have no more that half a beaker full.

The stink comes from sulfur compounds from the excess SMB, but a soak in 5% sulfuric acid should remove all the borax and sulfur.